Underreamer



F. SWAN.

UNDERREAMER.

APPLICATION FILED AuG.25, 1919.

Patend Mar. 29, 1921.

1&7299179 lll Il @ATENT .@FFHCE.

FRED SWAN, OF MARIETTA, OHIO.

UNDERREMER.

Application filed August 25, 1919.

Toall 'rcito/m t may concern.'

Be it known that l, FRED Swan', a citizen of the United States, residing at Marietta, in the county of )Vashington and State of Uhio, have invented certain new and useful Improvements in Underreamers, of which the following is a specification. l

My invention relates to an undeireamer for use in` the .boring of wells and ischar-` acterized by certain novel features of construction which particularly fit it for use in conjunction with well-casings of relatively large size'.

The construction and arrangement of parts is such that more than two cutters may be used, these cutters being held at top and bottoni in such manner as to permit of their beirig brought into collapsed position to permit their being lowered through the casing. while when in .their extended position they are solidly and iirmly held, so that an effective drilling blow may be struck.

The construction is illustrated in the accompanying drawings, in which- Figure 1 is a sectional elevation showing the underreamer in its collapsed position within the casing;

Fig. 2 is a sectional elevation showing the underreamer in extended position below the casing;

Figs. 3 and 4 are respectively a plan and an elevation of the retaining ring; and

Fig. 5 is a transverse section on plane 5-5 of Fig. 2.

Referring to thedrawings, 1 is the casing in the bore. 2 is a hollow mandrel provided at its upper end with a screw threaded socket for attachment to the drill stem, 3. lVit-hin the mandrel is a shouldered cavity in which is mounted a spring 4, resting at its lower end on the shoulder, and at its upper end bearing against a head 5 on a lifting bai' 6. T his bar extends throu h the end ot' the mandrel and has secured t 'iereto at its lower end, a cap or guide 7, which is of generally semi-spherical forni and has in its upper portion a cavity so shaped' as to receive the end of the mandrel and the lower lugs or ears 8, 8 of the cutters 9.

rlfhese cutters are, as shown in Fig. 5, four in number, though three or more than four may be used. They are preferably made of the shape and contigui-ation shown, the essential features being (1) that they shall Specification of Letters Patent.

` Patented Mar. 29, 1921.

serial nu. 319,636.

have annular faces 10,. to engage the corresponding face 11 of the retaining ring 42, this. face being preferably atA the angular inclination shown; (2) that they shall have surfaces 12 adapted toengage the coirespending tapered surface 13 of the mandrel; (3) that they shall have surfaces 14, which 1n the operating position of the tool'are at right angles to the axis of the tool; (4) that they shall have surfaces 21 adapted to engage a corresponding surface 22 on the mandrel; and (5) that they shall be provided at the top with ears or lugs 15, adapted to ext-end into corresponding cavities in the retaining ring 42, and at the bottom have ears or lugs 8 adapted to extend into corresponding cavities in the cap or guide 7.

The retaining ring 42 has riveted thereto, as yshown in Figs. 3 and 4, a diametrical cross-bar 16, which in turn extends through a slot in the lifting bar, 6. This ring has an inclined upper surface 17 adapted to engage the similarly inclined surface, 18, of an annular shoulder 19 of themandrel; and has at its lower end an inclined annular surface 11, and a cavity into which extend the ears or lugs 15 of the cutters.

By this arrangement, see Fig. 2, the ring is moved positively in unison with the cutters,

and the lu s v15 While retained by the walls of the cavity in the bottom of the ring are not in engagement therewith.

The mandrel has a slot 20, therethrough, t0 permit upward and downward lmoveiment of the bar 16. Other details of construction Will be apparent, without further description, from the drawings, which are made to scale.

In operation, the tool in its collapsed position, as shown in Fig. 1, is lowered through the casing. `When it passes below the end of the casing, the spring 4 pulls up on the cap 7, the cutters are wedged out because of engagement of surfaces 2l and 22, and move up, carrying with them the ring 42, until it,

engages the shoulder 19 on the mandrel 2. The underreaming is then carried on in the usual way.

lt will be notedv that while the cutters are, in a sense, loosely -held at top and bottom, they are in positive en agement, through the retaining ring with t e mandrel, so that a positive blow isgiven when the tool is dropped; and it will be further noted -that,

owing to the inclination given the engaging surfaces on the mandrel and cutters that these parts are in tirm and 'solid engagement transversely, as on the plane 5 5 of Fig. 2, and that because ol. these inclinations, the resultant direction of impact ofthe cutters on the mandrel is not perpendicular` to the axis but on a plane 30 (Fig. 2) normal to the conical end of the mandrel. As a result the boring tends to remain vertical with the maintenance of the shoulder 31. Should there be any tendency to deviationifrom the vertical line, the cap 7, entering the bore beneath the shoulder 31, serves to rectify the line of the boring.

I claim:

1.v An underreaming tool comprising a mandrel, a plurality of cutters surrounding the mandrel, separate retaining means engaging the cutters at top and bottom, and means for forcing the cutters into operative position.

2. A tool as claimed in claim 1, in which the forcing means comprises a spring pressed rod carried by but movable relatively to the mandrel.

3. A'tooLas claimed in claim 2, in which the upper retaining means comprises a ring secured to said rod, said ring having upper and lower surfaces `for engaging the mandrel and cutters respectively.

4. A tool as claimed in claim 3, in which the cutters have upwardly extendingelugs and the ring has a cavity into which the lugs extend.

5. A tool as claimed in clainn 3, in which the rod has secured at its lower end a cap bearing against the lower ends of the cutters,

said cap having a cavity into which extend downwardly extending lugs on the cutters.

(5. A tool as claimed in claim 2, in which the rod has secured thereto upper and lower retaining means between which the cut-ters are pivot-ally but loosely held.

7. A tool as claimed in claim in which the upper retaining means comprises a ring; tlxe'cutters have upwardly extending lugs and the'ring has a cavityinto which the lugs extend, and the lower retaining means comprises a 'cap having a cavity into which extend downwardly extending lugs on the cutters.

8. A tool is claimed in claim 3, in which the ring is secured to the rod by a bar passing through the rod and the mandrel has a slot through which the bar extends.

9. A tool as claimed in claim 1 in which the .forcing means comprise a movable spring-pressed member carried by the Inandrel and engaging the lower portions of the cutters, and cooperating wedging surfacesi 21 and 22 on the mandrel and cutters.

10. A tool as claimed in claim J in which the movable member carries a ring engaging upper inclined-surfaces on the cutters and a shoulder on the mandrel.

11. A tool as claimed in claim 1 in which the lower portions of the mandrel and the ycutters have coperating lateral thrust surfaces 12 and 13.

12. A tool. aslclaimed in claim 10 in which the cutters and ring have coperating, longitudinal thrust surfaces 10 and 11. f

in testimony whereof, I atiix my signature.

FRED SWAN. 

